Mercury-vapor lamp



M. J. CORNU.

MERCURY VAPOR LAMP.

APPLICATION FILED JAN-5, 191a.

1,3%3,@67., Patented June 8, 19200 wm/roz? War/wow?) Cor/7a STAT TENT OFFICE.

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mmcuar-vnroa LAMP.

Specification of Letters lfatent.

Patented June 8, 1920.

' Application filed January 5, 1918. Serial No. 210,583.

To all whom it may concern:

Be it known that I MARIE JosEPH' electric lamp. I

The mercury arc produced in this lamp is an arc of small length but of high specific brilliancy. It is produced between the two electrodes in a thick-walled quartz tube. The thickness being generally e ual to at least half the internal diameter 0 the tube, the heat of the arc is thereby retained, and the mercury vapor maintained at a high temperature.

There is no previously formed vacuum in the lamp. On the contrary, the internal pressure of the lamp at rest, as during normal working, is at least as great as the pres sure of the atmosphere.

The. cathode of the lamp is completely secured, that is to say, the mercury located therein cannot become displaced.

On the other hand-the anode is free, but with strong damping, the object of which is to brake its oscillations.

In the accompanying drawing, which illustrates by way of example one constructional form of the invention:

Figure l is a general view of the lamp at rest,

Fig. 2 illustrates the lamp during normal working,

Figs. 3, 4, 5, and 6 are devices for striking the are by means of heating by gas, electric glzhrjnent, automatic pump or expansion The cathode C is formed by a tube a, to which is connected the negative pole of the current supply, and which is united to a cooling chamber 6.

The anode A, which is connected to the positive pole of the current generator, comprises a test-tube 'c united through the medium of the bent tube at to the condensing chamber 6, which may or may not be provided with cooling vanes. The tube 0? terminates, in the middle of the test tube a, in

a very-narrow tube 7", into which there enters a fiat-headed metal pin 9 serving as a valve and only allowing the mercury to ass Very slowly. The test-tube c is close at its upper end and only allows assage for the spiral-shaped current-supp y terminal k pressing on' the head of the pin The cooling chambers e and b are unite to one another bythe quartz tube 73-7, exhibiting, in the immediate neighborhood of the cathode, a curvature is, the concavity of which is turned downward. The tube a'-j has 'its walls of thickness e ual to at least half the internal diameter 0 the tube;

The level of the mercury in the test tube a c rises for instance as high as Z-Z and, the extremity of the tube f being in the middle of the test tube, the lamp may be turned upside, down with impunity into any position whatever without fear of air getting into the inside.

The object of the device adopted for the anode is to damp the oscillations of the mercury and consequently to give fixity to' the arc.

I will now describe the operation of the lamp.

The lamp being filled right up and completely cleared of its gases, and current being supplied to the electrodes, all that is necessary in order to strike the arc is to produce the separation of the two meniscuses of mercury at the point is of the thick tube The arc may be struck in several different ways:

In Fig. 3 an external source of heat such as a gas heater m is utilized, which is placed in the neighborhood of the point is. As soon as the arc is struck, that is to say, as soon as the two mercury meniscuses are separated, the source of heat is removed.

In Fig. 4 the arc is struck by means of a heating spiral of platinum or other metal 11. wound around the quartz tube i-j and heated by the same electric current that actuates the lamp. The spiral may be cut out of circuit either by hand or automatically as soon as the arc is struck.

In Fig. 5 a capillary tube p-p is welded to the highest point of the thick tube i-j. By means of this tube an inert gas such as nitrogen, neon, argon, etc., or a vapor is introduced by means of a mechanical or automatic pump r. The gas or vapor under pressure pushes the meniscuses away to right and left. As soon as the are is produced one ceases to actuate the pump 1', in which the gas will resume its'place, and the lamp continues to'work.

In Fig. 6' the pum r is replaced by an expansion bulb s wel ed to the extremity of the capillary tube pp' and filled with the as that is to be introduced into the lamp.

his bulb incloses a heating filament 23 connected either in series or as a shunt to the terminals of the lamp, or on an independent circuit. When the current passes through the filament t it becomes heated, the gas expands and pushes away the meniscuses and the arc is started. As 'soon as the current is cut ofi, the bulb 8 becomes cool again, the gas resumes its place, and the mercury arc continues to work. 15

The internal pressure of the lamp may be whatever is desired. For that purpose it suffices either to increase or to decrease the height of anode test-tube and in this case the pressure is determined by the difi'erence between the level of the mercury at the point k and the level l-Z', or else to modify the pressure of the gas that fills the space above means for varying the pressure in the tube. 1

the mercury in the test-tube a. In this case the pressure is that which results from the adding together pressure of the gas inside and of the height of the column of mercury. Furthermore, if the anode A is hermetically sealed, the pressure inside the lamp tends to increase automatically when the arc becomes longer under the influence of an increase in the voltage at the terminals of the lamp.

What I claim is:

1. A mercury-vapor electric lamp, comprising a mercury tube having" cooling chambers and a thick walled-bent quartz portion connecting the chambers, the cathode end of the tube being closed and the anode end provided with means for damping the oscillations of the mercury, and

2. A mercury vapor electric lamp, comprising a mercury tube having cooling chambers and a thick walled bent portion connecting the chambers, the cathode end of the tube being closed and the other end 3. A mercury vapor electric lamp, comprising'a tube containing mercury and hav- 1ng cool1ng chambers and a bent portion havm a contracted passage and connecting the said chambers, the cathode end of the tube being closed and the other end reduced and open, a chamber forming the anode and into which extends the 0 en and reduced end of the tube, a valve or the said open end of the tube, a conductor, a spiral spring carried by the conductor and engaging and pressing on the valve, and meansfor forcing the mercury out ofthe said contracted passage.

4. n a mercury vapor electric lamp, a mercury tube having an intermediate bentquartz portion, and means for striking the arc,

comprising a capillary tube secured to'the quartz tube, an inert gas or vapor chamber with. which the capillary tube is connected,

and means for forcing the gas or vapor from the chamber into the bent portion of the mercury tube toexpand the same to cause the striking of the are independently of the vaporization of the mercury. v

5. In a mercury vapor electric lamp, a mercury tube having an intermediate bent and reduced portion, and means for striking the arc, comprising a capillary tube secured to the reduced portion of the mercury tube, an expansion gas bulb with which the capillary tube is connected containing an inert gas, and a heating filament in the bulb for expanding said gas to strike the arc.

In testimony whereof I have hereunto set my hand at Paris (France),this5th day of February, 1918.

a i MARIE JOSEPH CORNU. In the presence of,

CHAs. P. PRESSLY. 

